This invention relates generally to electrical connector assemblies for cathode ray tubes and, more particularly, to connector assemblies that are selectively releasable and that function effectively at high altitudes.
Conventional cathode ray tubes (CRT's) typically each include an integral glass stem on their rear sides, with a plurality of electrical contacts projecting rearwardly from the stem. The voltage levels of signals applied to at least one of the contacts can typically be on the order of 5000 to 7000 volts dc.
In applications limited to normal, sea level environments, where the air pressure is on the order of one atmosphere, the CRT stem is normally adapted to receive a mating plug assembly having contacts arranged and sized to mate with the contacts of the CRT stem. Insulating partitions are normally provided on the stem, to electrically isolate the high-voltage contact from the adjacent lower-voltage contacts. Such partitions are considered to provide adequate dielectric standoff at normal atmospheric pressures.
The connector assembly described briefly above does not operate effectively at altitudes, e.g., 40,000 to 70,000 feet, such as are encountered by military and commercial aircraft. At such high altitudes, the low air pressure significantly reduces the dielectric standoff between adjacent contacts. A voltage breakdown therefore can occur between the high-voltage contact and nearby lower-voltage contacts, unless special steps are taken to enhance the dielectric standoff. In the past, enhanced dielectric standoff typically has been achieved by soldering electrical conductors directly to the CRT contacts and then potting the entire assembly using an insulative silicone rubber material. This structure is effective at preventing a voltage breakdown, but has not proven to be entirely satisfactory, because it is not readily releasable. The connector assembly ordinarily must be destroyed to facilitate removal of the CRT for servicing or replacement. In addition, cold temperatures normally associated with high altitude applications, as well as thermal cycling, can adversely affect the integrity of the potting material.
It should, therefore, be appreciated that there is a continuing need for an improved CRT connector assembly that is readily releasable yet effective in providing sufficient dielectric standoff to allow effective operation even at high altitudes. The present invention fulfills this need.